Spns2 Transporter Contributes to the Accumulation of S1P in Cystic Fibrosis Human Bronchial Epithelial Cells

S1P/S1PR2 promote pancreatic stellate cell activation and pancreatic fibrosis in chronic pancreatitis by regulating autophagy and the NLRP3 inflammasome

Sphingosine-1-phosphate (S1P) is a bioactive lipid molecule that governs various functions by embedding its receptor, S1PR, in different cells. Chronic pancreatitis (CP) is characterized by pancreatic fibrosis via activation of pancreatic stellate cells (PSCs). However, the effect of S1P on CP and PSC activation is still unknown. Here, we conducted a series of experiments to explore the effect of S1P on a CP rat model and primary cultured PSCs. In vivo, CP was induced by intravenous injection of dibutyltin dichloride. S1P was administered at a dosage of 200 μg/kg body weight per day by intraperitoneal injection. After 4 weeks, serum, plasma and pancreas samples were collected for molecular analysis and histological detection. In vitro, PSCs were isolated and cultured for treatment with different doses of S1P. 3 MA and MCC950 were used to determine the effect of S1P on PSC activation by regulating autophagy and the NLRP3 inflammasome. JTE013 and Si-S1PR2 were applied to verify that the functions of S1P were realized by combining with S1PR2. Cells were collected for RT‒PCR, western blotting and immunofluorescence. The results showed that S1P was increased in the plasma and pancreatic tissue of CP rats. When S1P was administered to CP rats, the function and histomorphology of the pancreas were severely impaired. In addition, S1P promoted PSC activation, heightened autophagy and enhanced the NLRP3 inflammasome in vivo and in vitro. Moreover, S1PR2 mediated the effect of S1P on PSC activation by regulating autophagy and the NLRP3 inflammasome sequentially. In conclusion, S1P binding to S1PR2 promoted PSC activation and pancreatic fibrosis in CP by regulating autophagy and the NLRP3 inflammasome. These findings provide a theoretical basis for targeting S1P/S1PR2 to treat pancreatic fibrosis and further suggest that considering the role of autophagy and the NLRP3 inflammasome may help with the treatment pancreatic fibrosis.

Treatment with THI, an inhibitor of sphingosine-1-phosphate lyase, modulates glycosphingolipid metabolism and results therapeutically effective in experimental models of Huntington's disease

Huntington's disease (HD) is a fatal neurodegenerative disorder with no effective cure currently available. Over the past few years our research has shown that alterations in sphingolipid metabolism represent a critical determinant in HD pathogenesis. In particular, aberrant metabolism of sphingosine-1-phosphate (S1P) has been reported in multiple disease settings, including human postmortem brains from HD patients. In this study, we investigate the potential therapeutic effect of the inhibition of S1P degradative enzyme SGPL1, by the chronic administration of the 2-acetyl-5-tetrahydroxybutyl imidazole (THI) inhibitor. We show that THI mitigated motor dysfunctions in both mouse and fly models of HD. The compound evoked the activation of pro-survival pathways, normalized levels of brain-derived neurotrophic factor, preserved white matter integrity, and stimulated synaptic functions in HD mice. Metabolically, THI restored normal levels of hexosylceramides and stimulated the autophagic and lysosomal machinery, facilitating the reduction of nuclear inclusions of both wild-type and mutant huntingtin proteins.

Therapeutic CFTR Correction Normalizes Systemic and Lung-Specific S1P Level Alterations Associated with Heart Failure

Heart failure (HF) is among the main causes of death worldwide. Alterations of sphingosine-1-phosphate (S1P) signaling have been linked to HF as well as to target organ damage that is often associated with HF. S1P's availability is controlled by the cystic fibrosis transmembrane regulator (CFTR), which acts as a critical bottleneck for intracellular S1P degradation. HF induces CFTR downregulation in cells, tissues and organs, including the lung. Whether CFTR alterations during HF also affect systemic and tissue-specific S1P concentrations has not been investigated. Here, we set out to study the relationship between S1P and CFTR expression in the HF lung. Mice with HF, induced by myocardial infarction, were treated with the CFTR corrector compound C18 starting ten weeks post-myocardial infarction for two consecutive weeks. CFTR expression, S1P concentrations, and immune cell frequencies were determined in vehicle- and C18-treated HF mice and sham controls using Western blotting, flow cytometry, mass spectrometry, and qPCR. HF led to decreased pulmonary CFTR expression, which was accompanied by elevated S1P concentrations and a pro-inflammatory state in the lungs. Systemically, HF associated with higher S1P plasma levels compared to sham-operated controls and presented with higher S1P receptor 1-positive immune cells in the spleen. CFTR correction with C18 attenuated the HF-associated alterations in pulmonary CFTR expression and, hence, led to lower pulmonary S1P levels, which was accompanied by reduced lung inflammation. Collectively, these data suggest an important role for the CFTR-S1P axis in HF-mediated systemic and pulmonary inflammation.